Grade builder blade mounting



Oct. 26, 1948. H. WASHBOND 2,452,408

GRADEBUILDER BLADE MOUNTING Filed Nov. 29, 1943 5 Sheets-Sheet l 'VE U Oct. 26, 1948. H. WASHBOND 2,452,408

' GRADEBUILDER BLADE MOUNTING Filed Nov. 29, 1943 5 Sheets-Sheet 2 H. H. WASHBQND GRADEBUILDER BLADE MOUNTING Oct. 26, 1948.

5 Sheets-Sheet 3 Filed Nov. 29,-1943 Oct. 26, 1948.

H. H. WASHBOND 2,4524 GRADEBUILDER BLADE MOUNTING Filed Nov. 29, 1943 Sheets-Sheet 4 Oct H. H. wAHBoND 2,452,408 GRADEBUILDER BLAfiE Motmme Filed Nov. 29, 1943 5 Sheet Cs-Sheet 5,

5 E g? I Egg;

Patented Got. 26, 1948 ZASZAdd r OFFICE GRADE BUILDER BLADE MGUNTIN'G Harry H. Washbond, Springfield, Ill., assignor to The Baker Manufacturing Company, Springfield, Ill, a corporation of Illinois Application November 29, 1943, Serial No. 512,187

17 Claims.

This invention relates to gradebuilders having not the blade is in bulldoze or angledoze position.

Specifically the invention relates to gradebuilder blade mountings which tiltably support the blade on an axis which is always at right angles to the blade face.

Heretofore; gradebuilder blades have been pivoted on a yoke member which wasswivelly mounted on the push frame of a tractor. When these gradebuilder blades are positioned for angledozing the swivel mounting is at an acute angle relative to the blade face and tilting of the blade about a pivot point at an acute angle thereto will cause a tilting of the face of the blade. Thus, if the face of theblade is vertical in bulldoze position and theblade is then swung to angledoze position and next tilted about its swivel axis, the vertical face of the blade will be tilted at an angle to the vertical in. an amount dependent upon the extremity of the angledoze position or the acuteness of the angle between the blade and its swivel mounting.

As a result of the necessity for tilting gradebuilder blades when in angledoze position about an axis at an acute angle to the base of the blade, it was necessary to design the blade mounting structure with considerable looseness in the outer end retainers for the blade so as to compensate for the tilting of the blade. If the retainer structure had good fitting relation with the bladecarried structure, adjusting devices had to be provided to accommodate tilting of the blade.

In accordance with the present invention a center blade mounting is now provided which pivotally supports the blade on an axis that is always at right angles to the blade face irrespective of whether or not the blade is in bulldoze or angledoze position. The preferred blade mounting of this invention includes a yoke structure which rotatably carries the blade on a horizontal axis. This yoke structure is pivotally supported by the push beam frame on a vertcial axis. The vertical axis accommodates swinging of the blade between angledoze and bulldoze positions while the horizontal axis permits tilting of the blade. Since the horizontal axis swings with the blade, it is always at right angles to the blade face and therefore the blade always tilts about an axis in the same angular relation to the blade face.

Another feature of the invention resides in the 2 provision of arcuate anchoring means on the en portions of the blade which are struck fro-m radii centered on the horizontal axis of the center blade mounting. These anchoring means are elongated and project rearwardly from the rear face of the blade to provide a plurality of pinreceiving holes. Push beam frame-carried struts are equipped with retainers which cooperate with the arcuate anchoring means and have pinreceiving apertures therethrough capable of being aligned with the apertures in the anchoring means. Fastening pins are inserted throughthe aligned apertures'of the anchoring means and the retainers to hold the blade at the desired tilted angle. Since the arcuate anchoring means are struck from radii centered on the horizontal tilting axis for the blade, no looseness between the cooperating anchoring means and retaining means is required and accurate fit can be maintained. The blade is thus held firm and steady.

It is, then, anobject of this invention to pro vide a gradebuilder blade mounting which will not tilt the face of the blade'when the blade is tilted in an angledoze position.

A further object of the invention is to provide a blade mounting for gradebuilders 1 which is pivoted about a vertical axis on the push beam frame of a tractor and is rotatable about a horizontal axis on the gradebuilder blade.

A still further object of the invention is to provide a center blade mounting for tractor imple-' ment blades wherein the back face of the blade provides a bearing for a yoke piece which is pivotally mounted on the push beam frame of ,a tractor. x 1

A further object of the invention'is to provide improved gradebuilder mounting structure having cooperating push beam frame-carried and blade-carried retaining structure in snug fitting relationship. r

A still further object of the invention is to provide a firm and steady mounting for gradebuilder blades. Another object of the invention is to provide a shiftable strut-carried retainer for gradebuiler blades having snug fitting relationship with arcuate anchoring means on the gradebuilder blades.

A still further object of the invention is to provide a tilt support for implement blades which swings with the blade. 5.

Other and further objects of the invention will be appa ent to those skilled in the art from-the following detaileddescriptions of the annexed sheets of drawings which, by way of preferred 3 example only, illustrate one embodiment of the invention.

On the drawings:

Figure 1 is a top plan view of a tractor-mounted gradebuilder according to this invention.

Figure 2 is a front elevational view of the tractor-mounted gradebuilder shown in Figure 1.

Figure 3 is a rear elevational view of the grade builder blade shown in Figures 1 and 2.

Figure 4-. is a fragmentary side elevational view of the machine of Figures 1 and 2.

Figure 5 is an enlarged vertical cross-sectional view of the center blade mounting of this invention, with parts in elevation, taken along the line VV of Figure 1.

Figure 6 is a fragmentary rear elevational view of the center blade mounting taken along the line VI-VI of Figure 5 with parts being omitted.

Figure '7 is an enlarged vertical cross-sectional view, with parts in elevation, of the blade retainer structure of this invention, taken along the line VII-VII of Figure 1.

Figure 8 is a rear elevational view of the retainer structure, with parts in vertical cross section, taken along the line VIII-VII-I of Figure l.

' Figure 9 is a vertical cross-sectional view of the retainer structure of this invention taken along the line IX-lX of Figure 7.

Figure 10 is a fragmentary top plan view of a conventional prior art gradebuilder-mounting illustrating the blade in angledoze position.

Figure 11 is an end elevational view of the prior art structure of Figure 10 taken along the line XI--XI of Figure 10 and illustrating the tilted position of the blade face.

Figure 12 is a view similar to Figure 10 but illustrating the blade mounting structure of this invention.

Figure 13 isa view similar to Figure 11 taken along the line XIIL-XIIII of'Figure 12 and illustrating the straight vertical position of the blade face even when tilted in angle doze position.

As shown on the drawings:

In Figures 1, 2 and 4, the reference numeral l designates generally a tractor'having a main body portion l I, tractor track frames l2, rear and front toothed wheels l3 and i4, and endless tractor tracks I trained between the wheels I3 and I4 in toothed engagement therewith. The tractor track frames 1'2; near their rear ends, carry brackets IE pivotally supporting the rear ends of push beams l1. These push beams have upstanding arm portions 18 intermediate their ends projecting for a considerable distance above the tractor and connected at their upper ends by Figure 2. Hydraulic or pneumatic jack cylinders 2| are pivotedon the upper ends of the arms 20 and have piston-operated rods 22 pivoted to the arms Hi. The jacks 2l serve. to raise and lower the push beams relative to the tractor by swinging the beams about their pivot points on the brackets It. i

The front ends of the push beams I! are connected by a V-frame or cross beam 23 having a central apex point 24 at the axial center of the tractor.

struts 25 telescope into the front end of the push" beams ill and. have apertures therethrough adapted to-be aligned with any one of a pluralit'yof apertures'26 in the push beam for receiving locking pins 2'! to anchor the struts to project for a selected distance beyond the ends of the push beams.

As best shown in Figures 1 and 5, the apex 24 of the cross beam 23 has top and bottom plates 28 welded thereon and projecting forwardly therefrom. These plates 28 have aligned vertical apertures 28a therethrough receiving a vertical pivot pin 29.

As shown in Figures 5 and 6, a circular metal mounting piece 30 has a cylindrical collar 3| projecting from one face thereof and spaced opposed flat horizontal flanges 32 projecting from the other-face thereof. These flanges have vertical apertures 32a therethrough and carry apertured bosses 33 on the outer faces thereof. The pivot pin 29extends though the bosses 3.3 and apertures 32a.

In order to rigidify the flanges 32, side plates 34 are disposed between the flanges and are welded thereto. These side plates 34 extend from the plate 39 and converge into spaced opposed relation on each side of the pin 29. To further stiffen the flanges 32, the same are provided with downturned ears 35 welded to the circular plate 30.

A gradebuilder blade 36 composed of a concave front plate 31, an overlying scraping edge plate 38 welded to the front face of the plate 3'! at the bottom thereof, and spaced opposed top and bottom hollow box channels 39 welded to the rear face of the plate 3.! at the top and bottom ends thereof, has a square back plate 48 inserted between the channels 39 at the midpoint of the blade. This square plate 40 has top and bottom flanges 4| seated on the top and bottom channels 39 and a thickened central portion 42 with a horizontal aperture 43 therethrough receiving the collar 3! of the plate 30 in rotatable relation.

As shown in Figures 6 and '7, ribs 44' are welded on the back face of the plate 31 on each side of the square plate 40 and extend from the square plate to the outer end of the blade. Covering l plates 45 bridge the space between the box channels 39 on each side of the square plate 40 and are welded to these box channels. Plug wells 46 also anchor the plates 45 to the ribs 44.

The circular plate 30 is rotatably held on the square plate 4!] by means of four finger plates 47 best shown in Figure 6, which are bolted to the plate 43 by means of bolts 48 and overlie the peripheral portion of the end face of the plate 33. As shown in Figure 3 the square plate 40 has pairs of bolt holes 48a for receiving the bolts 48.

The blade 33 is thus rotatably mounted on the collar 31 of the circular plate 30 and this circular plate in turn is pivotally mounted on the push beam frame. The rotatable mounting for the blade 36 thus swings with the blade about the pivot pin 29 and its axis is always at right angles to the rear face of the blade.

As best shown in Figure 3, the blade 36 carries pairs of arcuate anchor flanges 59 on the rear face thereof near its outer ends. These flanges 50 project rearwardly from the rear face of the blade and are arcs of circles struck from radii R centered on the center point C of the bearing 43 provided by the square plate 40. As shown in Figures '7 and 9, the flanges 50 have a series of apertures 51 therethrough. These apertures are drilled on the same radii R from which the flanges 50 are struck.

As shown in Figures 4, '7 and 8, the front ends of the struts 25 have vertical hollow bosses 52 secured thereon receiving pins 53 for swivelly mounting retainer links 54 for the blade 36. Each link 54, as best shown in Figures 7 to 9, is built up from opposed angle pieces 55 having horizontal flanges 55a respectively overlying and underlying the boss 52 together with vertical flanges 55b on which are welded spaced opposed arcuate ribs 56 straddling the arcuate flanges 50. The horizon tal flanges 55a of the angle pieces are apertured for receiving the pin 53. Likewise the arcuate ribs 56 have top and bottom apertures adapted to be aligned with the apertures 51 of the flanges 50 for receiving pins 51. The pins 51 have heads 51a as shown in Figure 9 for abutting one rib 56 and have apertured end portions 511) for projecting beyond the other rib 56 to receive a locking rod 58 therethrough.

As shown in Figures 1, 8 and 12, the flanges 55a of the links 54 have a pair of holes therethrough for the pins 53. Thus, when the blade 36 is in bulldoze position, as shown in Figure l, the pins 53 extend through the innermost holes of the flanges 55a. but, when .the blade 36 is in angledoze position as shown in Figure 12, via, one of v the struts being fully telescoped into the push beam ll while the opposite strut 25 is being extended to its full outermost position from the other push beam H, the pin 53 is shifted to the outer hole on the pair of flanges 55a connected to the telescoped strut 25. The pins 53 are shifted from the innermost holes of the link 54 to the outermost holes to compensate for .the changes in positions of the flanges 50 relative to the struts 25 as the blade is swung about a vertical axis. The links 54 could be provided with more than a pair of holes for the pins 53 if intermediate angledoze positions for the blade 36 are desired.

Since the tilting bearing or horizontal pivot for the blade 36 always swings with the blade about the vertical pivot 29, the blade will always tilt about an axis at right angles to its vertical rear face irrespective of the angled position of the blade. Thus, as shown in Figures 12 and 13, the blade 35 may be mounted in full angledoze relation and then tilted as indicated in dotted lines in Figure 2 without causing any tilting or throwing forward of the face of the blade. This tilting of the face of the blade necessarily results in prior structure as shown in Figures 10 and 11 when the blade 35 is tilted in angledoze position, since it is swivelled about a pin 60 at an acute angle to the blade. In this prior art structure, the horizontal pivot 60 is swivelly mounted in the cross beam 23 andcarries a yoke 61 on which the center blade support 62 is pivotally mounted by means of a pin 53. Now as indicated in Figure 11, when the blade 36 is in angledoze position and is then tilted, its face will be tilted through ari angle A depending upon the acuteness of the angle between the swivel 60 and the rear face of the blade. Since the blade face 35 will be tilted, all retainer connections for the blade in the prior art structures must be quite loose to accommodate the tilting of the blade. In the structure of the present invention, on the other hand, the retainers can have snug fit and the blade will always be firmly held. Wear of the parts is reduced to a minimum because impact loads attendant with loose fitting parts are avoided.

The construction of the present invention is well adapted for accurate mass production since the square plate 40 need not be welded into final position until the outer end blade retainers are actually matedwith the strut-carried links. The

plate 40 can then be properly aligned with thepivot 29 and welded into position. The use of a circular plate 30 with a collar riding in a bearing on the plate 40, coupled with the use of the retaining fingers 41, provides an inexpensive yet efficiently operating and strong bearing structure. lhe bearing surfaces are substantially sealed from ingress of dirt and will operate freely over prolonged periods.

It will, of course, be understood that various details of construction may be varied through a wide range without departing from the principles of this invention and it is, therefore, not the purpose to limit the patent granted hereon otherwise than necessitated by the scope of the appended claims.

I claim as my invention:

1. In a gradebuilder adapted for attachment to a track-type tractor having side push beams connected at their front ends by across beam, an implement blade, and struts adjustably carried by the push beams, the improvements of a center blade mounting pivoted about a vertical axis on the cross beam and rotatable about a horizontal aXis on the blade, arcuate anchorin means on the end portions of the blade struck from radii centered on said horizontal axis, shiftable fastening means pivoted on said struts cooperating with said anchoring means to secure the blade in selected position on the push beams, and said shiftable fastening means having a plurality of vertical pivot axes for selective cooperation with the struts in accordance with the angle position of the blade.

2. The combination with a track-type tractor having a main body portion, track frames on the sides of said main body portion pivoted thereon, and endless tracks enveloping said track frames, of a gradebuilder attachment comprising a push frame having side arms pivotally mounted on said track frames and a V-shaped cross arm secured to the front ends of said side arms having an apex point at the axial center of the tractor, fluidpressure operated jacks interposed between said track frames and said side arms for raising and lowering the push frame relative to the tractor, a blade mounting device swingably mounted at the apex point of said cross arm about a vertical axis, a gradebuilder blade rotatably mounted on said swingable mounting device midway between the ends thereof, a pair of spaced opposed arcuate ribs projecting rearwardly from said blade adjacent each end of the blade and having a plurality of pin-receiving apertures .therethrough, struts telescopically mounted in said side arm .of the push frame having vertical pivots at their front ends, link-s having a plurality of pivot-receiving apertures to selectively receive said pivots on the struts, arcuate flanges on said links adapted to straddle the pairs of ribs on said blade and having pin-receiving apertures therethrough, and retainer pins adapted to be passed through the apertures of said flanges on the links and the apertures of said arcuate ribs to lock the blade in selected tilted relation relative to the push frame.

3. A gradebuilder attachment for tractors and the like which comprises a push frame having side arms and a V-shaped connecting arm with the apex thereof midway between said side arms and projecting forwardly therefrom, a vertical pivot pin carried by said cross arm at the apex thereof, a blade-mounting device having rearwardly projecting apertured bosses receiving said vertical pivot pin, a circular plate member on said mounting device, and a horizontal pivot projecting forwar-dly from said plate member, a gradebu-ild-er' blade, an: aperturediplategcn-the reanfacaof :said blade having an aperture therethrough receiving said; horizontal pivot of the. mounting device, fingers secured on said plate overlying-the circular plate portion .of'the mounting device torotatably se.curez.-tlie mounting device to-said blade, a pair of arcuate ribs projecting rearwardly from said blade at each end portionzthe-reof, said ribsbein arcs of circles struck from radii centered on the centenpointi Of the aperture in saidiapertured plate on the blade, retaining means for each pair of: arcuateribs having'flanges for snugly straddlingr-said ribs; eaehofjsaidzretaining means havinge. at; plurality: of" aligned" vertical apertures therethrough; strut-s, adjustably carried by the side arms of said push frame and adapted to project forwardly from said side arms at selected distances, each-of said'strutsliaving.verticalbosses atthe front, ends thereof, pins. pivotally connecting saichbosses. andsaid retainingmeans adapted EDI-b3? selectively seated in pairs of aligned vertical apertures on;the retaining means, saidflanges on the retaining means and said ribs having apertiiresrtherethrough, and pins"passedithroughsaid aperturestotlockthe blade in: selected tilted positions relativeto the push frame.

4 In-a grade. builderadap-ted for attachment to atractor: or thelike, apush frame having side arms-and a V-shaped cross-connecting armwith an; apex: point midway between said side arms, plates-welded to the top and bottom of said cross armzattheapex pointtthereof and projecting forwardly therefrom,ablade-mounting device having'a: circularrplate with means-projecting'rearwardly, therefrom between said-plates. on the cross arrrr, a vertical; pivot pin passed through said plates onzthe cross arm andsaid' rearwardly projecting" means toswingably mount said blademountingdevice: onthe cross arm, a horizontal collar; projecting forwardly from said circularplate. of said mounting device, a gradebuilder bladev having an apertured rear: wall member rotatably'mounted on said'collar, and fingers secured: on said rear: wall member of the blade overlyingsaid circularplate of the mounting devlcezforrholding said mounting device in rotatable relation relative to said blade whereby said blade can be swung torangled position relative to said pushframe; on said vertical pivot pin' and can be rotated: to tilted positions relative to said push frame without-tilting the face thereof.

5; Inza gradebuilder, animplernent' blade having; a: curved front wall; channel strips welded to: the. rear face of said front wall at the top and= bott0mthereof providing spaced opposed;

whereby said blade-mounting device will. swing:

with said. blade and; will tiltably support. the blade;

6; An implement blade; construction comprising; a: blade wall, boxchannel strips welded to the-rear f ace of .saidwall and-extending in spaced opposed; relation along thei lengthof the: wall;

said: strips providing. spaced opposed shelves on.

the..wall,,aplate having'top and bottom flanges securedionssaid shelves; acircular blade-mounting; devieeaoverlying said, plate. and having a pivot projecting intcnsaid plate iri.rotatable-:rela;-

tion. therewith; retainer members 1 secured onsaid-v plate overlying said circular mounting device to rotatably securethe mounting device onthe plate,

and pivot support means projecting rearwardly;

from the circular portion of said'mounting device. adapted to be swingably mounted on another support.

7. An implement blade construction comprising a curved scraper plate, elongated hollow box channels welded to the rear face of said plate along the top and bottom ends thereof and defining spaced opposed shelves, a mounting plate secured to said box channels to the rear of said curved scraper plate, a blade-mounting device rotatably mounted on said mounting plate, ribs secured tothe rear face of said curved scraper plate between said box channels and extending along the length of the plate, and covering plates between said box channels anchored to said ribs.

8. The combination with a gradebuilder blade and a strut having a vertical pin boss on the end thereof, of a pair of spaced opposed ribs secured on said blade and projecting rearwardly therefrom, said ribs having a plurality of apertures along the lengths thereof, a retainer link having top and bottom flanges for straddling said strut pin boss and having forwardly projecting flanges for straddling said ribs, said top and bottom flanges having a plurality of sets of aligned apertures therethrough, a pin extending through a pair of said aligned apertures and through said pin boss pivotally mounting the link on the strut, and a pin passed through the apertures of the flanges and ribs to connect the blade to the link.

9. In a road machine, a yoke-like frame whose side arm portions are pivotally mounted on the machine on horizontal axes and having a front portion extending across the front of the machine, clevis means on said frame front portion intermediate the sides thereof, a pivot bracket including a bored block and a plate, a vertically disposed pivot bolt removably extended through said clevis means and the bore of said block, a. mold board having spaced upper and lower. recessed shelves on its inner face intermediate the ends thereof and a socket therebetween, and a.

- recessed shelves.

10. In a road machine, a yoke-like frame whose side arm portions are pivotally mounted on the machine on horizontal axes and having a front. portion extending across the front of the machine, clevis means on said frame front portion intermediate the sides thereof, a pivot bracket including an apertured protuberance and a plate, a vertically disposed pivot bolt removably extended through said clevis means and the apertui'ed protuberance, amold board having spaced recessed shelves on its inner face intermediate the ends thereof and a socket'therebetween, and a pivot stud on said bracket, plate engaging said mold board socket, opposite edges of said bracket plate being movably engaged in said recessed shelves.

11. In a road machine, a yoke-like frame whosev with an apex point at the axial center of they machine, a pivot bracket including a vertically apertured protuberance with a rigidly attached plate, saidplate having opposed curved edges,,a vertically disposed pivot bolt extending through the aperture of said protuberance, there also being means adjacent the apex of said yoke-like frame through which said pivot bolt extends, a mold board having spaced opposed shelves provided with recesses conforming to the curved edges of said plate and rotatably receiving the latter, there being a socket in said mold board intermediate said shelves, and a pivot stud on said bracket plate engaging said mold board socket and forming an axis for rotatable movement of the plate.

12. In a bulldozer, the combination of a U- shaped supporting frame, having a vertical hole in the center of the U; a blade, having two undercut arcuate recesses facing each other on the rear face thereof; an attaching member having a fiat vertical plate portion, opposite edges of which are designed to register loosely with said two recesses respectively, and having at least one rearwardly projecting lug with a vertical hole therein to register with the vertical hole in the U; and a pin for insertion in these holes.

13. An attachment for vehicles such as tracktype tractors and the like which comprises a push frame having side arms and a connecting cross arm, a blade mounting device swingably mounted about a vertical axis on said cross arm for accommodating angling of a blade, a blade rotatably mounted on said mounting device, blade-anchoring struts adjustably mounted on the side arms of the push frame to project forward from the cross arm at selected distances, links pivotally mounted on said struts, means selectively connecting said links with said blade for holding the blade in adjusted tilted position, and said links having adjustable mountings relative to said struts to laterally shift the links for maintaining proper alignment with the blade-mounting means irrespective of the angled condition of the blade.

14. In a gradebuilder construction having an implement blade and an anchoring strut to angle the blade, the improvement of a multi-apertured elongated upstanding rib secured on the rear face of the blade and projecting rearwardly therefrom, a shiftable retainer device having an apertured elongated rib for fitting alongside of the bladecarried rib, pin means adapted to extend between aligned apertures of the ribs to lock the blade and retainer together, spaced opposing mounting flanges on said retainer adapted to straddle said strut, said mounting flanges having a plurality of sets of laterally spaced aligned apertures therethrough, and a pin pivotally connecting said retainer with said strut at a selected position on the strut to maintain close-fitting relation between said ribs irrespective of the angled position of the blade.

15. An implement blade assembly comprising a frame having side arm and a cross beam, a

blade mounted on said cross arm for tilting and angling movement, struts telescoped in said side arms, means selectively locking said struts for projecting forwardly from the side arms in variable length increments to accommodate angling of the blade, retainers on said struts, said retainers having spaced opposed angle members with vertical flanges and horizontal flanges, said horizontal flanges straddling said struts and having a plurality of sets of holes therein, pins extending through said holes and struts for pivotally anchoring the retainers on the struts in adjusted lateral positions, ribs secured to said vertical flanges of the retainer, anchoring ribs on said blade adapted to be positioned adjacent the ribs on said retainers, said ribs on the retainers and on the blade having a plurality of holes therethrough, and pins passed through aligned holes of the retainer ribs and the blade-carried ribs to lock the blade in adjusted tilted position.

16. A blade assembly comprising a supporting frame including side beams and a cross beam, a blade-mounting device pivoted on said cross beam for swinging movement about an axis accommodating angling of the blade relative to the frame, said blade-mounting device having a plate portion, a blade having undercut recesses receiving the edges of said plate portion therein for rotatably mounting the blade on the blade-mounting device to accommodate tilting of the blade relative to the frame, and means anchoring the blade on said frame for holding the blade in adjusted position relative to the frame.

17. In a bulldozer or the like machine the combination of a supporting frame of substantially U shape, a blade-mounting device pivotally mounted on the bight portion of said frame for swinging movement about a vertical axis, said blade-mounting device having a plate portion swingable about said vertical axis, an implement blade having opposed undercut recesses on the rear face thereof receiving said plate portion therein in relatively rotatable relation, and means anchoring said blade portion in adjustable tilted position relative to said frame.

HARRY H. WASI-IBOND.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,961,011 Pearson May 29, 1934 1,977,817 Bird Oct. 23, 1934 2,044,933 Buffington June 23, 1936 2,059,431 Barrett et a1. Nov. 3, 1936 2,162,993 Austin June 20, 1939 2,308,535 Paulsen Jan. 19, 1943 

